Method and apparatus for control of base stations in macro diversity radio systems

• US 6,104,933 A
• Filed: 06/23/1997
• Issued: 08/15/2000
• Est. Priority Date: 06/23/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Almgren, Magnus, Frodigh, Magnus, Kronestad, Fredric, Gudmunson, Mikael
• Primary Examiner(s): Trost, William G.
• Assistant Examiner(s): Trinh, Sonny
• Application Number:
  US08/880,746
• Time in Patent Office: 1,149 Days
• Field of Search: 455/67.3, 455/67.7, 455/69, 455/226.2, 455/226.3, 455/522, 455/524, 455/525, 455/560, 455/561
• US Class Current: 455/522
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A method and apparatus for controlling an amount of downlink power to be applied in each downlink transmission in a macro diversity radio system. Downlink power level is controlled in response to a quality measurement of a corresponding uplink. In accordance with exemplary embodiments, a path gain or a carrier-to-interference ratio of an uplink is measured at a base station in an active set, and subsequently used to proportionally govern a downlink transmission power level for a corresponding downlink. In such a fashion, each downlink handling a mobile station maintains a desired level of robustness, while avoiding introduction of unnecessary system interference.

Claims

1. A method for controlling transmission power used in a downlink signal from a base station to a mobile station in a macro diversity radio system, the method comprising the steps of:

measuring a quality of an uplink signal received in the base station from the mobile station; and

controlling more than one downlink signal so that a greatest amount of downlink signal transmission power is allocated to an active set link receiving a highest quality uplink signal.

2. The method of claim 1, wherein a greatest amount of downlink signal transmission power is allocated to an active set base station receiving a highest quality uplink signal.

3. The method of claim 1, wherein a greatest amount of downlink signal transmission power is allocated to an active set antenna link corresponding to a highest quality uplink signal.

4. The method of claim 1, wherein the step of measuring a quality of an uplink signal comprises:

measuring a path gain in the uplink signal.

5. The method of claim 1, wherein the step of measuring a quality of an uplink signal comprises:

measuring a carrier-to-interference ratio of the uplink signal.

6. The method of claim 1, wherein the step of measuring a quality of an uplink signal is selected from the group consisting of:

measuring a bit error rate for the uplink signal, and measuring a frame erasure rate for the uplink signal.

7. The method of claim 1, wherein the step of measuring a quality of an uplink signal comprises:

measuring a quality of a carrier signal component of the uplink signal.

8. An apparatus for controlling transmission power used in a downlink between a base station and a mobile station in a macro diversity radio system, the apparatus comprising:

means for measuring a quality of an uplink signal received in the base station from the mobile station; and

means for controlling more than one downlink signal so that a greatest amount of downlink signal is allocated to an active set link receiving a highest quality uplink signal.

9. The apparatus of claim 8, wherein a greatest amount of downlink signal transmission power is allocated to an active set base station receiving a highest quality uplink signal.

10. The apparatus of claim 8, wherein a greatest amount of downlink signal transmission power is allocated to an active set antenna link corresponding to a highest quality uplink signal.

11. The apparatus of claim 8, wherein the means for measuring a quality of an uplink signal comprises:

means for measuring a path gain in the uplink signal.

12. The apparatus of claim 8, wherein the means for measuring a quality of an uplink signal comprises:

means for measuring a carrier-to-interference ratio of the uplink signal.

13. The apparatus of claim 8, wherein the means for measuring a quality of an uplink signal is selected from the group consisting of:

means for measuring a bit error rate for the uplink signal, and means for measuring a frame erasure rate for the uplink signal.

14. The apparatus of claim 8, wherein the means for measuring a quality of an uplink signal comprises:

means for measuring a quality of a carrier signal component of the uplink signal.

15. A method for selecting a base station for inclusion in an active set of base stations communicating with a mobile station in a macro diversity system, the method comprising the steps of:

measuring a quality of an uplink signal received in the base station from the mobile station;

comparing the quality of the uplink signal with a predetermined quality requirement; and

including the base station in the active set if the quality of the uplink signal meets or exceeds the predetermined quality requirement;

wherein a number of base stations that can be added to the active set is dependent on a current traffic load.

16. A method for controlling transmission power used in a downlink signal from a base station to a mobile station in a macro diversity radio system, the method comprising the steps of:

measuring a quality of an uplink signal received in the base station from the mobile station; and

controlling downlink signal transmission power in response to the measure of quality of the uplink signal;

wherein an amount of downlink signal transmission power is proportional to the measure of quality of a corresponding uplink signal and an amount of downlink signal transmission power, P_i, for a link i in an active set follows the proportion governed by;

##EQU4## where;

P is a total power available;

g_i is a path gain for the uplink of link i; and

n is a number of communication devices in the active set.

17. The method claimed in claim 16, wherein g_i is an average path gain for the uplink of the link i.

18. The method claimed in claim 16, wherein the links are base station links and the communication devices are base stations.

19. The method claimed in claim 17, wherein the links are base station links and the communication devices are base stations.

20. The method claimed in claim 16, wherein the links are antenna links and the communication devices are antennas.

21. The method claimed in claim 17, wherein the links are antenna links and the communication devices are antennas.

22. A method for controlling transmission power used in a downlink signal from a base station to a mobile station in a macro diversity radio system, the method comprising the steps of:

measuring a quality of an uplink signal received in the base station from the mobile station; and

controlling downlink signal transmission power in response to the measure of quality of the uplink signal;

wherein an amount of downlink signal transmission power is proportional to the measure of quality of a corresponding uplink signal and an amount of downlink signal transmission power, P_i, for a link i in an active set follows the proportion governed by;

##EQU5## where;

P is a total power available;

C_i /I_i is a carrier-to-interference ratio for the uplink of the of link i; and

n is a number of communication devices in the active set.

23. The method of claim 22, wherein C_i /I_i is an average carrier-to-interference ratio measured for the uplink of the link i.

24. The method claimed in claim 22, wherein the links are base station links and the communication devices are base stations.

25. The method claimed in claim 23, wherein the links are base station links and the communication devices are base stations.

26. The method claimed in claim 22, wherein the links are antenna links and the communication devices are antennas.

27. The method claimed in claim 23, wherein the links are antenna links and the communication devices are antennas.

28. An apparatus for controlling transmission power used in a downlink between a base station and a mobile station in a macro diversity radio system, the apparatus comprising:

means for measuring a quality of an uplink signal received in the base station from the mobile station; and

means for controlling the amount of transmission power used for the downlink signal power, the amount of transmission power being based on the quality of the uplink signal measured;

wherein an amount of downlink signal transmission power is proportional to the measure of quality of a corresponding uplink signal and an amount of downlink signal transmission power, P_i, for a link i in an active set follows the proportion governed by;

##EQU6## where;

P is a total power available;

g_i is a path gain for the uplink of link i; and

n is a number of communication devices in the active set.

29. The apparatus of claim 28, wherein g_i is an average path gain for the uplink of the link i.

30. The apparatus of claim 28, wherein the links are base station links and the communication devices are base stations.

31. The apparatus of claim 29, wherein the links are base station links and the communication devices are base stations.

32. The apparatus of claim 28, wherein the links are antenna links and the communication devices are antennas.

33. The apparatus of claim 29, wherein the links are antenna links and the communication devices are antennas.

38. The apparatus of claim 30, wherein the links are antenna links and the communication devices are antennas.

34. An apparatus for controlling transmission power used in a downlink between a base station and a mobile station in a macro diversity radio system, the apparatus comprising:

means for measuring a quality of an uplink signal received in the base station from the mobile station; and

means for controlling the amount of transmission power used for the downlink signal power, the amount of transmission power being based on the quality of the uplink signal measured;

wherein an amount of downlink signal transmission power is proportional to the measure of quality of a corresponding uplink signal and an amount of downlink signal transmission power, P_i, for a link i in an active set follows the proportion governed by;

##EQU7## where;

P is a total power available;

C_i /I_i is a carrier-to-interference ratio for the uplink of the link i; and

n is a number of communication devices in the active set.

35. The apparatus of claim 34, wherein C_i /I_i is an average carrier-to-interference ratio measured for the uplink of the link i.

36. The apparatus of claim 34, wherein the links are base station links and the communication devices are base stations.

37. The apparatus of claim 35, wherein the links are base station links and the communication devices are base stations.

39. The apparatus of claim 35, wherein the links are antenna links and the communication devices are antennas.